FORT MEADE, Maryland (Reuters) - U.S. soldier Bradley Manning's release of secret files to WikiLeaks in the biggest breach of classified data in the nation's history helped Al Qaeda's recruiting efforts, an expert on radical Islam testified on Thursday.

The militant group used Manning's releases to claim that "the United States does not value human life," particularly among Muslims, said Navy Commander Youssef Aboul-Enein, an adviser to the Pentagon's Joint Intelligence Task Force for Combating Terrorism.

Manning, 25-year-old Army private first class, was convicted last week on 19 charges for providing more than 700,000 diplomatic cables, battlefield videos and other classified data to the WikiLeaks pro-transparency website.

His court-martial has moved into a sentencing phase, with prosecutors trying to persuade Judge Colonel Denise Lind to impose a lengthy sentence. He could face up to 90 years in prison on the counts Lind found him guilty of.

Manning's defense attorneys will also have an opportunity to call their own witnesses in coming days.

Testifying for the prosecution, Aboul-Enein said al Qaeda used a video Manning had provided to WikiLeaks of a U.S. helicopter gunship in 2007 firing at suspected insurgents in Baghdad. A dozen people were killed, including two Reuters news staff.

The helicopter also fired at a truck in which a child was seated, seriously wounding him.

Al Qaeda used the video to demonstrate to Muslims that "this could be your child," Aboul-Enein said.

Under questioning by defense lawyer Major Thomas Hurley, Aboul-Enein said propaganda had long been a central function of al Qaeda unrelated to WikiLeaks.

"So if it wasn't WikiLeaks, it would be something else?" Hurley asked.

"Yes," Aboul-Enein said. He added that since a 2011 al Qaeda video, the group's leadership had been largely silent about the leaked documents.

Aboul-Enein, the day's only witness, also said al Qaeda had not claimed any tactical successes because of the WikiLeaks information.

Manning was a low-level Army intelligence analyst when he leaked files to WikiLeaks while serving in Iraq in 2010. He was convicted of charges that include theft and espionage and faces up to 90 years in prison when his sentencing hearing concludes, which is expected later this month.

Manning was found not guilty of the most serious charge of aiding the enemy. His lawyers portrayed the slightly built soldier as naive but well intentioned, and argued that his aim was to provoke a broader debate on U.S. military policy.

Manning's court-martial has drawn international scrutiny, and the trove of documents he provided catapulted WikiLeaks and its founder, Julian Assange, into the spotlight. (Editing by Ian Simpson and Andrew Hay)

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